From the Bill of Rights Defense Committee on National Security Letters.
May 23, 2008
Good overview of the secret life of current US law enforcement
National security letters are a major tool of current US law enforcement, and they are problematic. A major issue is the "gag" component that makes it so that if a recipient tells anyone they even got one (except their lawyer) they can go to jail.
The Internet Archive got one and fought it, but we were one of 3 out of 200,000 to do so publicly.
A good little movie to watch, in my opinion.